The demand for communication bandwidth is ever increasing. Fiber optic communication provides an excellent solution to this requirement and techniques like spatial domain multiplexing (SDM) can increase fiber capacity by many folds. SDM adds a new dimension in optical fiber multiplexing techniques by allowing spatially separated, co-propagating channels of the same wavelength over a single strand of optical fiber thereby increasing the fiber capacity. These channels follow helical path, and each channel is confined to a dedicated radial distance from the center of the fiber. The centermost channel generally exits the output end of the fiber in the form of a spot while the outer channels appear as concentric rings.
As compared to a standard fiber communication system, the SDM system requires two additional components; the multiplexer or the beam combination module (BCM) and the demultiplexer or the beam separation module (BSM). Current setup of SDM systems employ a lens/photodiode combination for de-multiplexing of spatially multiplexed channels. This requires tedious alignment and is prone to environmental perturbations.